Insulating shield for electrolytic tanks



\ Nov. 26, 1946. T I s. BQSANFORD ETAI. 1 3L INSULATING SHIELD FOR ELECTROLYTIC TANKS Filed De'c. 27, 1943 Patented Nov. 26, 1946 INSULATING SHIELD FORELECTROLYTIC' TANKS Selden Bradley Sanford, Yonkers, N. Y., and WilliamGeorge Nutzel, Nutley, N. J assiimorsv to Otis Elevator Company, New. York, N. Y., a' corporation of New Jersey I I Application December 27, ieia seriai 515,338

The invention relates lytic processes. V, p a

In practicing electrolytic processes it is essential that there be no direct electrical contact between th electrodes, In some of these processes, a metal lining for the tank is utilized as an electrode. This is the case, for example, in the process of forming artificially on aluminum articles a protective coating composed substantially of aluminum oxide, known as anodizing.

While the process employed to form such oxide coatings on aluminum may vary, depending principally upon th use or after treatment of the article, in one process widely used, thealuminum surface is treated electrolytically as anode in an aqueous solution of sulphuric, acid. In this process a lead lined tank is employed and this lining is utilized as the cathode. 1 i

The object of th inventionis to provide a durable insulating shieldafor use in an electrolytic processing tank, especially a metal lined tank 'in whichthe lining is utilized as an electrode.

In-carrying outtheinvention according to the preferred arrangement, the insulating shield is formed of a plurality of spaced main members and a plurality of cross members extending between the main members. Along the bottom, the main members extend across the tank and the cross members longitudinally of the tank. Along the sides, the main members extend vertically and serve as posts while the cross members extend around the sides and ends of the tank, preferably in the form of a spiral. Between the main members and preferably parallel thereto are warp members with which the cross members are interwoven to provide a mesh like structure. All of these members are of an insulating plastic which is chemically resistant to the electrolyte. Thus a basket like insulator is formed which does not restrict the flow of current between electrodes, which obviates any direct contact between electrodes, and which lasts indefinitely.

Features and advantages of the invention will become apparent from the following description and appended claims.

The invention willbe described as applied to an anodizing tank.

In the drawing:

Figure 1 is a plan view of an electrolytic processing tank embodying the invention; and

Figure 2 is a view in section, taken along the line 22 of Figure 1.

Referring to the drawing, the tank l may be made of any suitable material, such as sheet to apparatus for electro- I 2 Claims-, (01. 204-279) iron or reinforced wood. It is provided with a lead lining Ii which is not affected by an aqueous solution of sulphuric acid employed as the electrolyte. :In the anodizing process, the temperature of the solution is an important factor and for this reason a coil lZ-bf lead pip is provided within the tank through which hot or cold v water may bepassed to'control the temperature.

tween the sides.

It is also important that the temperature, throughout the solution be uniform. To obtainthis-result, the solution is agitated by air admitted to the tank through the lead pipe [3.

This pipe has a deadend and runslongitudinally of the tank along the bottom and midway beinto the electrolyte. v e

The insulating shield may be fabricated in three sections, one Of which forms the bottom li and the other two the sides l6.- Each section comprises-a plurality of main members H, a, plurality of cross members [8 and a plurality; of warpmembers 20. These members are of 'nonmetallic electrolyte resistant material and are preferably made of tubing. A bendable plastic material such as Saran which is synthetic resin comprising polymers derived from vinylidene' chloride has been found especially suitable for.

bers for the bottom section are at right angles to the main members. As regards the sides, the main members, after being drilled, are sawed off at increasing distances from the bottom so that when the shield is installed these cross members may form a continuous spiral.

The warp members 20 are positioned between the main members in parallel relation thereto. The warp members may be of the same diameter as the cross members and may be either of straight pieces of tubing as illustrated adjacent the ends of the bottom section or of longer pieces of tubing bent over upon themselves to form two warp members joined at one end in the nature of a hairpin as more clearly shown in Figure 2 for a side section. The cross members I8 are interwoven with the warp members, being bent alternately under and over the warp members as illustrated to form a-basket weave construction.

, Outlet holes. not shown, are provided in the pipe through which the airpasses After each side section has been assembled it is bent at the corners to fit the tank inside the lead coil. With material such as Saran a permanent set may be made by immersing in boiling water for about a minute and then cooling in tap Water. The side sections are then joined by joining the ends 22 of the abutting cross members with tubular insert (not shown). The bottom section is inserted in the tank first and is bent down on each side from theair'pipe 13: The:- joined side sections are then inserted, meshing:-

them at the bottom with the bottom section to hold this section in place Whentheelectrolyteis: admitted to the tank. The main members of -the side section may be close together atthe corners:

as illustrated to facilitate meshing with the bottom section. The bottom section may alsobetied; to the lead pipe I2 to assist in holding it in.

position.

The number and size of the various members making up the'insulating shield may vary depending upon the particular installation. For example; in a tank, 4 feet-Wide by 8 feet long by 5feet deep, for which an insulating shieldhasbeen constructecLthe main members are made of limb tubing and-the cross members and warp membersof inch tubing, Most of the main members are spaced about 17 inches and the cross members are spaced 1 inches. The Warp members-are spaced about 2%; inches. This gives a sufiiciently stiff construction to insure no direct contact of anode with the cathode or pipes while at the same time it provides meshes of ample size not to materially restrict the circulation of electrolyte or flow of currentloetween electrodes.

While described in connection with a tank utilized for anodizing, the invention has other applications. As many changes could bemade in theabove construction and many apparently widely different embodiments of this invent-ion could be madewithout' departing from the scope thereof,- it is intended that all matter contained in the above description or'shown in the accompanying drawing shall be interpreted-as illustrative and not in a limiting sense;

What is claimed is:

1. An insulating shield for an electrolytic processing tank having ametal'lining' serving as an form an-upwardlyextending spiral, and all of said members being of, bendable tubing of synthetic resin resistant" to the chemical action of the electrolyte.

2. Aninsulating shield for an electrolyticv processing tank having a, metal lining serving as an electrode comprising; a section for shielding the bottomof the-tank; and apai-r of'sectionsfor shielding the side and end walls of' th'e-tank each" section compri-sing, a plurality of 'spaced main=members each having a plurality of 'cross 1 apertures equally spaced lengthwise thereof, a

plurality of cross members extendingthroughsaid apertures, and a pluralityof warp members between and: parallel to said main members with which the cross member are interwoven, the main members of the bottom shielding section extending crosswise-of the bottom of the tank andthose-of'said pair of sideand endshielding sections extendingvertically, said pair of side and end shielding sectionsbeing bent to fit the'tank at the corner and the ends of the'cross members thereof being joined in abuttingrelationship with the relationship of said apertures in the main members thereof such that thesecross-members form: a continuous upwardly extending spiral, said-pair of side andend shielding-sections intermeshing with the bottom shieldin g section when the sections 'are'in place in'thetank, and all of" said members of all sections being tubing of tli'e'rmoplasti'c synthetic resin comprising polymers derived' from vinylidene chloride.

SELDEN BRADLEY SANFORD. WILLIAM GEORGENUTZELQ 

